1 CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
Carbon fiber reinforced plastic CFRP is a complex profile of a polymer
bonded to carbon fiber. This composite exhibits a very high strength to weight ratio and coped with high rigidity makes an ideal application in many industries such as
aerospace, automotive, motor racing and sports. The wings of an Airbus and the body frame of a competition bike are examples where CFRP is useful to give great
strength and yet remain light weight. The fusion of carbon fiber and resin is done through curing process. Curing process refers to the hardening of a polymer material
achieved through cross linkage of polymer chains. Curing process is done with the aid of heat, electron beams, chemical additives, or even ultraviolet radiation. In the
rubber industry, curing of rubber is known as vulcanization. There are several ways to induct a curing process of CFRP.
Pre-impregnated laminate composite or known as prepreg is a composite fiber
with existence of matrix material within it. Conventional method would require liquid resin to be applied onto the fiber in a closed mold. For that purpose, the epoxy
resin, the fabric and resin hardener are prepared according to the right proportion before molding takes place. On the other hand, prepreg comes in a complete set with
sufficient amount of both resin and hardener already impregnated in the fabric matrix. That is the huge difference between using conventional composite
preparation and prepreg. Prepregs have been the most common choice nowadays in the industries worldwide due to its simplicity.
After undergoing curing process, the CFRP induces a permanent deformation known as the springback. Such deformation from the desired shape causes
impediments during the assembly process and higher scraps rate. Even if the deformed parts were joined by force, the level of the internal stress will further
increase and thus shorten the life expectancy of the component. Deep understanding of springback phenomena is required to produce quality components to accommodate
high manufacturing rate for the production of modern aircraft such as the Airbus A320. Springback deformation occurs due to the stress build up during the
crystallization of the resin within the composite. Therefore, warpage acts onto the composite after curing process. Based on previous research, three different
mechanisms were identified as the source of the stress generated by the curing process. Those mechanisms are chemical reaction, thermal condition and finally the
interaction between the tool and the laminate.
Experimental parameters which play an important role on the springback are
divided into two categories which are intrinsic parameters and extrinsic parameters. Intrinsic constraints refer to the physical parameters of the laminate composite such
as the length, thickness, number of plies and shape. Extrinsic constrains on the other hand denotes manufacturing process parameters such as surface condition, tool
material, cure cycle and pressure of the autoclave.
1.2 PROBLEM STATEMENT
Kategori